Sericho is an officially approved meteorite name. It belongs to the pallasites, one of the rarest and most visually striking meteorite groups, made of iron–nickel metal with embedded olivine crystals. This combination of metal and “gem-like” olivine islands is what creates the famous decorative look of pallasites.
Sericho was found in 2016 in Eastern Kenya, near the Habaswein area and south of Sericho (in the wider Isiolo region). This is not an observed fall but a find: nobody witnessed it falling, and it was discovered already lying on the ground surface.
According to the reported story, in 2016 two brothers searching for their camels came across several large, unusually dense “stones” in an area with almost no natural rocks. That strongly suggested they were meteorites. Over several weeks they collected the masses using hoists and moved them to Habaswein. Interestingly, although the material was recognized as meteoritic in 2016, local people had known about some of the large masses for many years, even decades—some accounts say children used to play on top of them.
Sericho stands out not only for its beauty but also for the large amount of material recovered. More than 2800 kg (about 2.8 tonnes) has been reported.
Fragments occur across a long strewnfield extending over 45 km. Sizes vary dramatically, from pieces under 1 kg up to masses of hundreds of kilograms, with some specimens reaching roughly 500 kg. Most recovered pieces are large, often above 50 kg. Some specimens are described as “flight-oriented,” meaning they preserve clear aerodynamic shaping from their passage through the atmosphere.
Many pieces found on the surface show minimal external weathering. In places, patches of fusion crust remain on the metal. Many specimens are blocky and angular, with characteristic shallow depressions often compared to “thumbprints.”
When the meteorite is cut, polished, and often etched, the classic pallasite structure appears: olivine “islands” set in a silvery-grey metallic framework. Sericho’s olivine is often described as gemmy, ranging from green to orange tones, which makes polished slices exceptionally decorative. Because olivine can be abundant, thin slices may transmit light, creating a stained-glass-like effect.
In many slices Sericho shows a broadly similar metal-to-olivine relationship: on average, about 70% of the area is olivine, while chromite is present only in very small amounts. In some local zones, a single slice can contain even more olivine.
Olivine grains are commonly rounded and more rarely well-formed. Typical crystal sizes are around 0.5–1 cm, with occasional grains several centimeters across. The metallic portion is dominated by kamacite; plessite occurs in places, and in rarer metal-rich zones a Widmanstätten pattern may develop. Accessory phases such as troilite and schreibersite can also occur.
Sericho’s olivine has a relatively low iron component (often expressed as a fayalite content around Fa12). In the metallic portion, kamacite typically contains around 7 wt% nickel. Overall, Sericho is classified as a pallasite with a low degree of weathering, consistent with the fresh appearance of many recovered specimens.
Pallasites are considered some of the most fascinating meteorites because they display the boundary between two very different materials: metal and silicates. The most widely used explanation is this:
In the early Solar System, a small asteroid heats up due to radioactive decay (especially short-lived isotopes). It partially or extensively melts and begins to differentiate: the heavier iron–nickel metal sinks inward to form a core, while silicate material forms a mantle.
For pallasites, many researchers link them to the zone where the metallic core contacts the silicate mantle. If mixing occurs along this boundary, olivine crystals can become incorporated into the metal. Another scenario involves major impacts: a collision can disrupt the boundary regions, mix metal and mantle fragments, and then the material cools, “freezing” olivine within a metallic framework.
Why do pallasites look so spectacular? Olivine can be translucent and richly colored, while iron–nickel metal, when polished and etched, reveals internal structures (such as Widmanstätten patterns). The beauty is not accidental—it reflects slow, large-scale physical processes in space.
It helps to separate two kinds of “age.”
First is cosmic age. Nearly all meteorites are extremely old, commonly formed in the early Solar System about 4.56 billion years ago. Pallasitic material is also tied to very early differentiation processes inside small bodies.
Second is terrestrial age: how long the meteorite has been on Earth after it fell. Because Sericho is a find rather than an observed fall, the exact fall date is unknown. However, the low degree of weathering and the relatively fresh look of many pieces allow a cautious inference that at least some material may have fallen relatively recently in geological terms (hundreds to a few thousand years). This is not a guarantee, because weathering rates depend strongly on climate, soil chemistry, whether the piece remained exposed or became buried, and other factors.
Local accounts that the stones were known for “decades,” and that older people remember them from childhood, suggest that at least the larger masses have been there for a long time. Still, that alone cannot reliably distinguish between a fall a few hundred years ago and one several thousand years ago.
